Zhou Shifeng

Transparent Ni2+-Doped MgO-Al2O3-SiO2 Glass Ceramics with Broadband Infrared Luminescence

We report transparent Ni2+-doped ZnO-Al2O3-SiO2 system glass-ceramics with broadband infrared luminescence. After heat-treatment, ZnAl2O4 crystallite was precipitated in the glasses, and its average size increased with increasing heat-treatment temperature. No infrared emission was detected in the as-prepared glass samples, while broadband infrared luminescence centered at 1310 nm with full width at half maximum (FWHM) of about 300 nm was observed from the glass-ceramics. The peak position of the infrared luminescence showed a blue-shift with increasing heat-treatment temperature, but a red-shift with an increase in NiO concentration. The mechanisms of the observed phenomena were discussed. These glass-ceramics are promising as materials for super broadband optical amplifier and tunable laser. (c) 2006 Elsevier Ltd. All rights reserved.

Tunable Infrared Luminescence and Optical Amplification in PbS Doped Glasses

PbS-doped glasses are prepared. Absorption and luminescence spectra show that both the absorption and infrared emission can be tuned widely by thermal treatment conditions. Optical amplification at 1300nm is observed, and amplified spontaneous emission (ASE) spectrum is also measured to confirm the optical gain from PbS quantum dots.

Blue-to-Orange Tunable Luminescence from Europium Doped Yttrium–Silicon–Oxide–Nitride Phosphors

Europium-doped yttrium–silicon–oxide–nitride phosphors are synthesized by carbothermal reduction and nitri-dation method. The crystal structure of the phosphors changed gradually from oxide Y2 Si2 O7 to nitride YSi3 N5 state with increasing dosage of Si3N4 and carbon powder. The Y2 Si2 O7: Eu phosphor shows a blue emission at 465nm with 300nm excitation and a characteristic red emission of Eu3+ at 612nm with 230nm excitation. The YSi3 N5: Eu phosphor shows a broad emission band centred at 595nm with some sharp peaks of Eu3+ with 325nm excitation. The absorption of the studied phosphors increases from 450 to 700 nm with an increment in nitrogen content. Blue-to-orange tunable luminescence is observed with 390 nm excitation.

Broadband Near-Infrared Emission from Transparent Ni2+-Doped Sodium Aluminosilicate Glass Ceramics

Broadband near-infrared emission from transparent Ni2+-doped sodium aluminosilicate glass-ceramics is observed. The broad emission is centred at 1290 nm and covers the whole telecommunication wavelength region (1100–1700 nm) with full width at half maximum of about 340 nm. The observed infrared emission could be attributed to the 3T2(F)→3A2(F) transition of octahedral Ni2+ ions that occupy high-field sites in nanocrystals. The product of the lifetime and the stimulated emission cross section is 2.15×10−24 cm2s. It is suggested that Ni2+-doped sodium aluminosilicate glass ceramics have potential applications in tunable broadband light sources and broadband amplifiers.

Structural Change in Au3+-Doped BK7 Glass Irradiated by Femtosecond Laser

We report on structural change in an Au3+-doped BK7 glass irradiated by an infrared femtosecond laser at 800 nm. A grating structure is inscribed in the glass sample. The glass sample is then annealed at various temperatures. Structural change of the grating is observed by an optical microscope. Absorption spectra indicate that colour centres are induced after the laser irradiation, and they decrease with increasing annealing temperature. Au nanoparticles are precipitated at high temperatures (≥600°C). The mechanisms of the phenomena are discussed.

Broadband Infrared Luminescence of Ni2+ in Petalite-Type Transparent Glass Ceramics

Transparent Ni2+-doped magnesium aluminosilicate glass ceramics are prepared. The formation of petalite-type crystallites in the glass ceramics is confirmed by x-ray diffraction. Broadband infrared luminescence centred at around 1235 nm with full width at half maximum (FWHM) of about 300 nm is observed from the Ni2+-doped glass ceramics. The observed infrared emission could be attributed to the 3T2(F)→3A2(F) transition of octahedral Ni2+ ions in petalite-type crystallites. The product of the fluorescence lifetime and the stimulated emission cross sections is 1.2×10−24 cm2s.